Production of vat dyestuffs of the dibenzanthrone series



Patented Mar. 28, 1933 UNITED STATES PAUL NAWIASKY, or LUDWIGSHAFEN-ON-TBEE-RHINE; Ann: 'JIULIUs MUELLER, or

MANNHEIM, GERMANY, ASSIGNORS TO GENERAL. ANILINE woEKs, INC:,'.0F YOR-K,1\T.Y.,A CORPORATION OF DELAWARE' 1 I PEoDUo'rIoN 0E VAT DYESTUFFS oE'rHE DIBENZANTH-RQNE SERIES Q I No Drawing. Original application filed September 22, .1826, Serial. No. 221,396,. and in Great Britain February 14, 1927. Divided and this application filed. August4,.1928. Serial 297,551.

The present invention relates to the production of new vat dyestuffs.

The subject-matter of this application has been divided out from our copending application for the production of new vat dyestuffs Ser. No. 221,396, filed September 22, 1927, which has matured into U. S. Patent No. 1,742,317, dated January 7, 1930.

We have found that valuable new vat dyestuffs are produced by treating with alkaline agents the aminobenzanthrone obtainable by reducing the nitrobenzanthrone described in Example 2 of the U. S. Patent No. 876,679. If, f0 example, the said aminobenzanthrone be f sed with alcoholic potash, a brilliant green dyestufi is obtained. Other vat dyestuffs may be obtained by employing other alkaline agents or varying the conditions with regard to proportions, temperature and the like. Similar valuable .vat dyestufl s, which are often identical with the green dyestulf just described are obtained by treating substitution products of the aforesaid aminobenzanthrone, which contain exchangeable substituents in the Bz-l-position, or the N- acylated derivatives thereof with alkaline agents. The temperature employed for the treatment with alkaline agents will generally range between about and 200 C.

The green dyestuffs prepared according to the methods above described are transformed V by the action of oxidizing agents into brown vat dyestuffs of excellent fastness. The brown dyestuffs may also be produced on the fibre, by treating the dyeings made with the said green dyestuffs with oxidizing agents such as hypochlorites, fast brown dyeings being produced.

Similar brown vat dyestufi's are also obtained in a simple manner by treating the beforementioned nitrobenzanthrone directly with alkaline agents. The resulting dyestuffs may be purified by treatment with oxidizing agents such as hypochlorite.

The following examples will serve to further illustrate the nature of the said invention but the invention is not limited to these examples. The parts are by weight.

Example 1 5 parts of the dyestuff, obtained according to Example 1 of U. S. Patent No. 1,742,317,, datedjdanuary 7, 1930, are brought into a state of fine distribution and suspended in glacial acetic acid. Asolution of10-parts of-chromic' acid in14t00 parts of'water is then run in gradually'at waterbath' temperature,

and the whole. is heated on the waterbath for several hours. The dyestuffs after being filtered.v off by suction and washed untilneutral, is then boiled with dilute hypochlorite solution, until the shade,as determined by means of a test portion, is no longer altered. The resulting dyestufi gives handsome, brown, very fast dyeings on cotton from a dark blue vat. The solution of the dyestufl in sulfuric acid is violet with a reddish tinge. We think it probable that the oxidation proceeds inaccordance with the following equation b o I o 0 +20= H I 2H2O co co Example 2 10 parts of cotton are dyed, in any lmown or suitable manner, from the warm hydrosulfite vat with 02 part of the green dyestuii' obtained according to Example 1 of U. S. Patent No. 1,742,317, dated January 7, 1930, and are then treated for a quarter of an hour with a dilute solution of bleaching powder containing from 0.3 to 0.5 per cent of active chlorine. The original green changes to a rich brown. The reaction proceeds probably as indicated in Example 1.

What we claim is: a 1. The process of producing a new valu able brown vat dyestuff which comprises treating with an oxidizing agent the vat dyestuflf obtainable by treating in an alcoholic V caustic potash melt at between 120. and 200 7 C. aminobenzanthrone, which is derived from 10 the nitrobenzanthrone obtainable by treating benzanthrone with nitric acid in boiling glacial acetic acid.

' 2. Th'e process ofproducing a new valuable brown vat dyestufi which comprises treating with hypochlorite solution the vat dyestuflt obtainable by treating in an alcoholic caustic potash melt at between 120 and 200 C. aminobenzanthrone, which is obtainable by reducing the nitrobenzanthrone obtainable by treating benzanthrone with nitric acid in boiling glacial acetic acid.

In testimony whereof, we afiix our signatures.

' PAUL NAWIASKY. I v JULIUS MUELLER. 

